[Sync] Add ability to save/restore Nigori to SyncEncryptionHandlerImpl

components/sync_driver/sync_frontend.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_SYNC_DRIVER_SYNC_FRONTEND_H_
 #define COMPONENTS_SYNC_DRIVER_SYNC_FRONTEND_H_
 
 #include "base/basictypes.h"
 #include "sync/internal_api/public/base/model_type.h"
 #include "sync/internal_api/public/sync_encryption_handler.h"
@@ skipping 116 matching lines @@
 
   // Called to perform migration of |types|.
   virtual void OnMigrationNeededForTypes(syncer::ModelTypeSet types) = 0;
 
   // Inform the Frontend that new datatypes are available for registration.
   virtual void OnExperimentsChanged(
       const syncer::Experiments& experiments) = 0;
 
   // Called when the sync cycle returns there is an user actionable error.
   virtual void OnActionableError(const syncer::SyncProtocolError& error) = 0;
+
+  // Called when the user of this device enables passphrase encryption.
+  //
+  // |nigori_state| is the updated nigori state.

[Nicolas Zea, 2015/06/11 17:43:07]

Maybe be a bit more specific and explain that nigori_state preserve's the new
encryption keys, and explain what the frontend is expected to do with it.

[maniscalco, 2015/06/15 16:49:18]

Done.

+  virtual void OnLocalSetCustomPassphrase(
+      const syncer::SyncEncryptionHandler::NigoriState& nigori_state) = 0;
 };
 
 }  // namespace sync_driver
 
 #endif  // COMPONENTS_SYNC_DRIVER_SYNC_FRONTEND_H_